My blower is under powered. It does not perform as promised on the box. I work at Home Depot and I have sold this product to customers because of the amazing performance in the store. We demo with the 4.0. What I got was a 2.0 and Disappointment. It only worked well enough in Turbo for 10 min. I was able to borrow the 4.0 from the store. that was the difference. I would love to pay the difference and trade in my 2.0 for a 4.0. How can I do this?